/*
 * Copyright � 2002-2011 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using System.Collections;
using System.Reflection;
using System.Runtime.Serialization;
using Spring.Core.TypeResolution;
using Spring.Util;
using Spring.Reflection.Dynamic;

namespace Spring.Expressions;

/// <summary>
/// Represents parsed method node in the navigation expression.
/// </summary>
/// <author>Aleksandar Seovic</author>
[Serializable]
public class ConstructorNode : NodeWithArguments
{
    private SafeConstructor constructor;
    private IDictionary namedArgs;
    private bool isParamArray = false;
    private Type paramArrayType;
    private int argumentCount;

    /// <summary>
    /// Create a new instance
    /// </summary>
    public ConstructorNode()
    {
    }

    /// <summary>
    /// Create a new instance
    /// </summary>
    public ConstructorNode(Type type)
        : base(type.FullName)
    {
    }

    /// <summary>
    /// Create a new instance from SerializationInfo
    /// </summary>
    protected ConstructorNode(SerializationInfo info, StreamingContext context)
        : base(info, context)
    {
    }

    /// <summary>
    /// Creates new instance of the type defined by this node.
    /// </summary>
    /// <param name="context">Context to evaluate expressions against.</param>
    /// <param name="evalContext">Current expression evaluation context.</param>
    /// <returns>Node's value.</returns>
    protected override object Get(object context, EvaluationContext evalContext)
    {
        object[] argValues = ResolveArguments(evalContext);
        IDictionary namedArgValues = ResolveNamedArguments(evalContext);

        if (constructor == null)
        {
            lock (this)
            {
                if (constructor == null)
                {
                    constructor = InitializeNode(argValues, namedArgValues);
                }
            }
        }

        object[] paramValues = (isParamArray ? ReflectionUtils.PackageParamArray(argValues, argumentCount, paramArrayType) : argValues);
        object instance = constructor.Invoke(paramValues);
        if (namedArgValues != null)
        {
            SetNamedArguments(instance, namedArgValues);
        }

        return instance;
    }

    /// <summary>
    /// Determines the type of object that should be instantiated.
    /// </summary>
    /// <param name="typeName">
    /// The type name to resolve.
    /// </param>
    /// <returns>
    /// The type of object that should be instantiated.
    /// </returns>
    /// <exception cref="TypeLoadException">
    /// If the type cannot be resolved.
    /// </exception>
    protected virtual Type GetObjectType(string typeName)
    {
        return TypeResolutionUtils.ResolveType(typeName);
    }

    /// <summary>
    /// Initializes this node by caching necessary constructor and property info.
    /// </summary>
    /// <param name="argValues"></param>
    /// <param name="namedArgValues"></param>
    private SafeConstructor InitializeNode(object[] argValues, IDictionary namedArgValues)
    {
        SafeConstructor ctor = null;
        Type objectType = GetObjectType(this.getText().Trim());

        // cache constructor info
        ConstructorInfo ci = GetBestConstructor(objectType, argValues);
        if (ci == null)
        {
            throw new ArgumentException(
                String.Format("Constructor for the type [{0}] with a specified " +
                              "number and types of arguments does not exist.",
                    objectType.FullName));
        }
        else
        {
            ParameterInfo[] parameters = ci.GetParameters();
            if (parameters.Length > 0)
            {
                ParameterInfo lastParameter = parameters[parameters.Length - 1];
                isParamArray = lastParameter.GetCustomAttributes(typeof(ParamArrayAttribute), false).Length > 0;
                if (isParamArray)
                {
                    paramArrayType = lastParameter.ParameterType.GetElementType();
                    argumentCount = parameters.Length;
                }
            }

            ctor = new SafeConstructor(ci);
        }

        // cache named args info
        if (namedArgValues != null)
        {
            namedArgs = new Hashtable(namedArgValues.Count);
            foreach (string name in namedArgValues.Keys)
            {
                this.namedArgs[name] = Expression.ParseProperty(name);
            }
        }

        return ctor;
    }

    /// <summary>
    /// Sets the named arguments (properties).
    /// </summary>
    /// <param name="instance">Instance to set property values on.</param>
    /// <param name="namedArgValues">Argument (property) name to value mappings.</param>
    private void SetNamedArguments(object instance, IDictionary namedArgValues)
    {
        foreach (string name in namedArgValues.Keys)
        {
            IExpression property = (IExpression) namedArgs[name];
            property.SetValue(instance, namedArgValues[name]);
        }
    }

    private static ConstructorInfo GetBestConstructor(Type type, object[] argValues)
    {
        IList<ConstructorInfo> candidates = GetCandidateConstructors(type, argValues.Length);
        if (candidates.Count > 0)
        {
            return ReflectionUtils.GetConstructorByArgumentValues(candidates, argValues);
        }

        return null;
    }

    private static IList<ConstructorInfo> GetCandidateConstructors(Type type, int argCount)
    {
        ConstructorInfo[] ctors = type.GetConstructors(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);
        List<ConstructorInfo> matches = new List<ConstructorInfo>();

        foreach (ConstructorInfo ctor in ctors)
        {
            ParameterInfo[] parameters = ctor.GetParameters();
            if (parameters.Length == argCount)
            {
                matches.Add(ctor);
            }
            else if (parameters.Length > 0)
            {
                ParameterInfo lastParameter = parameters[parameters.Length - 1];
                if (lastParameter.GetCustomAttributes(typeof(ParamArrayAttribute), false).Length > 0)
                {
                    matches.Add(ctor);
                }
            }
        }

        return matches;
    }
}
